The primary goal of this program is to further our understanding of the molecular basis of thrombotic disease. In this regard, the group of eight clinical and basic scientists have joined together to undertake fundamental studies on blood coagulation and related phenomena. These studies include structural studies on fibrinogen and fibrin, platelet physiology and biochemistry, the biocompatability of materials, fibrinolysis and thrombin inhibitors. During the forthcoming year it is anticipated that the complete primary and secondary structures of human fibrinogen will be obtained. The data already have provided great insight into the molecular basis for the formation of fibrin. Also, it is expected that the nature of interaction between platelet collagenase and platelet factor 4 will be completely elucidated. Studies on factors VII, IX and X and their interaction during the activation of prothrombin will also be continued, including studies on abnormal factor IX molecules. Studies on the absorption of plasma proteins to surfaces will continue. Promising leads in the area of synthetic plasminogen activators will also be followed up, as will a variety of studies involving synthetic polypeptides.